Structure and Function of the Cocoon of a Ceratophryd Frog

Abstract

Lepidobatrachus llanensis (Leptodactylidae) were found to form cocoons when exposed to dry conditions, either in air or soil. We studied the effect of cocoon formation on rates of water loss from intact animals. When first removed from water L. Ilanensis lost water at rates comparable to typical anurans under similar conditions (ca. 8 mg g-lhr-1), but within three to four days the cocoon began to form and water loss decreased 50 to 70% within a week. Rates of water loss from two individuals excavated after 150 days in dry soil were 1.08 and 0.55 mg g-lhr-1, or 7 to 14% of the rates of animals taken directly from water. While burrowed in relatively dry soil, L. llanensis differed from spadefoot toads (S. couchi) in not accumulating high concentrations of urea and thus did not reduce the water potential of their body fluids below that of the soil. Nevertheless, they lost less water and showed smaller increases in plasma electrolytes than did S. couchi under identical conditions.